\begin{tikzpicture}
    \tkzDefPoints{0/0/O}
    \tkzDefPoint(135:1.5){A}
    \tkzDefPoint(45:1.5){B}
    \tkzDefShiftPoint[A](0,-.4){E}
    \tkzDefShiftPoint[B](0,-.4){F}
    \tkzDefLine[mediator](A,B)  \tkzGetPoints{c}{d}
    \tkzInterLL(E,F)(c,d)  \tkzGetPoint{C}
    \tkzDefShiftPoint[C](0,-2.5){D}
    \tkzDefShiftPoint[C](-0.4,0){G}
    \tkzDefShiftPoint[G](0,-2.5){H}

    \tkzDrawCircle[thick](O,A)
    \tkzDrawPolygon[fill=white](A,B,F,C,D,H,G,E) % 为了遮挡住 D 点附近的圆弧
    \tkzDrawPolygon[pattern={mylines[angle=45, distance={4pt}]}](A,B,F,C,D,H,G,E)
    \tkzDrawPoint(O)
    \tkzLabelPoints[left](A)
    \tkzLabelPoints[right](B,D)
    \tkzLabelPoints[below right](C)
\end{tikzpicture}

